Seat construction

ABSTRACT

Base structure for seat means including a U-shaped support member having four upright legs defining two substantially parallel planes, said member being secured by connection means to a rigid, substantially horizontal frame member of the seat means. Said base structure and seat means may be arranged to permit stacking. A pair of runners are attached near the central portions thereof to the lower ends of the legs in parallel relationship to each other and transversely of said planes for engagement with a supporting surface.

United States Patent [151 3,695,693

Acton et al. 1 Oct. 3, 1972 SEAT CONSTRUCTION 3,000,669 9/ 1961 Silverman ..297/451 72 Inventors: H h C. Acto R T hi 3,031,227 4/1962 Van Buren ..297/239 Kalgamazoo 35, 31 v f fi 3,494,662 2/1970 Schaefer et al. ..297/24s Pmage Mlch- FOREIGN PATENTS OR APPLICATIONS [731 Assgnw Cmpmm! Kalamam 478,756 l/l938 Great Britain ..297/239 1,150,233 8/1957 France ..297/445 [22] Filed: Aug. 6, 1970 585,512 2/ 1947 Great Britain ..297/239 reat mam 39 1 pp No 61 707 575 965 3/1946 G B 297/2 Primary Examiner-Francis K. Zugel [52] us. Cl ..297/239, 297/445 Att ney- 0 a Blanchard & Flynn [51 Int. Cl ..A47c 3/04 [58] Field of Search.....' ..297/239, 248, 445, 457; [57] ABSTRACT 248/188 188's; 108/91 Base structure for seat means including a U-shaped 5 6] References Cited sugport {:fimbel' liilzlalvilng fiour uprigllct1 legs debfiningJ two su stantl y par e p anes, saI mem er emg UNITED STATES p secured by connection means to a rigid, substantial] NTS h tal f b f h S 'd b y onzon rame mem er 0 t e seat means. a1 ase ,?g7,586 8/1960 Hoven .108/144 Structure and Seat means may be arranged to permit 3,762 5/1964 Newman ..,-297/248 Stacking. A pair of runners are attached near the 3,351,378 11/1967 B1158 ..297/248 1 portions thereof to the lower ends of the legs in 3,476,342 11/ 1969 Motlet a1. ..297/445 X parallel relationship to each other and transversely f g g gg said planes for engagement with a supporting surface. n r 3,235,309 2/ 1966 Foster et al. ..297/445 X 9 Claims, 9 Drawing Figures SEAT CONSTRUCTION BACKGROUND OF THE INVENTION This invention relates in general to a seat construction and, more particularly, to a base or support structure for seat means, which base structure is capable of stacking, capable of use with a variety of seat means, resistant to tipping, sufficiently resiliently flexible to give greater comfort to the occupant of the seat means, and designed to minimize wear on or damage to the supporting surface.

Persons acquainted with the manufacture and use of chairs, seats and similar devices for supporting human beings will immediately recognize that the hereinafter described invention provides a completely new departure in seat base constructions. In particular, the base structure for the seat overcomes or avoids a number of problems which have been virtually inherent in chairs since they were first built. Specifically, many conventional, four-legged chairs are easy to tip, particularly in a backwards direction where the occupant is almost helpless to prevent his own injury which is often serious.

The conventional chair is virtually inflexible. That is, the base structure is such that it well nof flex when it is occupied. Thus, any change in the position of the occupant necessitates an adjustment of the occupant to the chair, because the chair, or seat thereof, will not adjust with the occupant.

It is difficult to clean the floor around a conventional chair and, as a rule, the chair must be moved. The upright legs of the conventional chair are constantly in the way and in a short period of time clearly confirm this fact by the nicks and mars thereon. In spite of efforts to the contrary by manufacturers, the legs of the conventional chair make virtually pinpoint contact with their supporting surface. Accordingly, carpeting, tile, wood or any other known conventional supporting surface in homes, schools, offices and the like soon become torn, worn, gouged, dimpled or scratched by chair legs.

It is well known that chairs used in schools, institutions and the like are advantageously capable of stacking when not in use in order to minimize storage space. Many types of stackable chairs have been developed, but the commercially acceptable types are designed with individual legs for pinpoint contact with the floor or other supporting surface.

Chairs of the type used in residences or offices must be readily capable of variations in color and style to accommodate demands of decor. Usually, this is accomplished by modifying the seat and back structures. Thus, there has been a real need for an attractive, sturdy base or support structure which can be quickly and easily attached to a wide variety of seat and back arrangements in order to satisfy individual needs and tastes.

Accordingly, a primary object of this invention is the provision of a seat construction having base structure rigidly secured to the seat means but capable of flexing in order to permit some movement of the seat means relative to the supporting surface when said seat means is occupied, and wherein the base structure includes elongated runners which engage the supporting surface along an extensive area so that wear on or damage to the supporting surface by the base structure is at least reduced if not eliminated.

A further object of the invention is the provision of a base structure for a seat construction which has greater than average resistance to tipping backwards and which minimizes lateral tipping by virtue of the location and extent of said runners, said base structure being capable of use with and adaptation to a wide variety of seat means to provide chairs, benches, couches and the like.

A further object of this invention is the provision of a seat construction, as aforesaid, which creates a minimum of interference for cleaning operations around the seat construction, which is capable of stacking, which avoids structural failures by avoiding conventional stress points and which minimizes obstruction to movement of the occupant of the seat means around the seat means.

Other objects and purposes of this invention will be apparent to persons familiar with this type of equipment upon reading the following descriptive material and examining the accompanying drawings, in which:

FIG: 1 is a perspective view of a seat construction having a base structure embodying the invention;

FIG. 2 is a fragmentary front elevational view of said seat construction;

FIG. 3 is a sectional view substantially as taken along the line III-Ill in FIG. 2;

FIG. 4 is a broken sectionalview taken along the line IVIV in FIG. 2;

FIG. 5 is a broken fragment of FIG. 2 as viewed from the cutting line V-V;

FIG. 6 is a fragment of FIG. 4 illustrating a modified structure;

FIG. 7 is a side elevational view of a plurality of said seat constructions arranged in stacked positions;

FIG. 8 is a sectional view taken along the line VIII- VIII in FIG. 7; and

FIG. 9 is a front elevational view of a modified seat construction embodying the invention.

For convenience in description, the terms upper, lower, from, rear and words of similar import will have reference to the seat construction as appearing in FIG. 2, for example, wherein the front side of the seat construction is shown. The terms inner, outer and derivatives thereof will have reference to the geometric center of said seat construction and parts thereof.

SUMMARY OF THE INVENTION The objects and purposes of the invention, including those set forth above, are met by providing a base structure having a U-shaped support member including crossbar means and a pair of substantially parallel legs extending downwardly from the opposite ends of said crossbar means. The crossbar means of the support member is attached to a rigid frame member that is part of a seat means. A pair of parallel, substantially coextensive runners are connected to the lower extremities of the legs, one runner being on each side of the chair.

DETAILED DESCRIPTION The seat construction, here a chair 1 0 which is illustrated in FIGS. 1 and 2, comprises an occupant engaging portion having a seat 11 and back 12 which, in this particular embodiment, are formed in a molding operation as integral members made from plastic impregnated with fiberglass. However, other materials may be used. A seat cushion 13 may be supported upon the seat 11, and upholstering may be used as desired. The seat, back and cushion of said chair may be, and preferably are, substantially conventional in structure, provided that said seat 11 has a relatively rigid part engageable from below it.

The chair 10 (FIG. 1) has a base structure 15 which, in combination with the seat 11, comprises the novel improvement in said seat construction. Specifically, the base structure 15 comprises a pair of elongated support elements 16 and 17 which are U-shaped and fabricated from steel rod in this particular embodiment. However,

other metals or plastics might be used, and the elements 16 and 17 can be tubular, either round or rectangular in cross section.

Support element 16 has a crossrod l8 and a pair of parallel legs 19 and 20 which extend substantially perpendicularly from the crossrod 18, except for a slight radius at their connections with the crossrod 18. The support element 17 has a crossrod 23'and a pair of legs 24 and 25 which are arranged so that they are preferably identical with the arrangement of legs and crossrod in the element 16. While the legs 19,20 and 24,25 are illustrated as being parallel, their may be circumstances where it is desirable to have legs 19 and 24 diverge slightly downwardly with respect to the legs 20 and 25, respectively, to facilitate stacking operations discussed hereinafter.

The lower ends of the legs 19 and 24 (FIGS. 4 and 5) are flattened at 27 and 28, respectively, in order to facilitate their connection, as by brazing or welding, for example, to the runner 29. It will be observed in FIG. 8 that the flattening is accomplished so that the sides thereof engaged with the runner are slightly beyond the plane defined by the corresponding outer edges of the legs above the flat portions. This arrangement accomplishes two purposes, namely, it permits stacking and it moves the point of maximum deflection and stress upwardly away from the runner which at least reduces the chances of breaking the connection between the legs and the runner. In this embodiment, the distance between the legs 19 and 24 or the legs 20 and 25 is preferably approximately twice the thickness of any one of said legs. This arrangement permits the stacking disclosed in FIG. 7.

The lower ends of the legs 20 and 25 also have flat portions, as shown at 32 in FIG. 2 with respect to the leg 20, which flat portions are secured by welding or brazing to the central portion of a runner 33. The runners 29 and 33 are preferably parallel for normal use and preferably perpendicular to the legs 19,24 and 20,25. However, under some circumstances, it may be desirable to cant or slope the legs forwardly or rearwardly relative to the runners 29 and 33 and this application contemplates such possibility. Although the runners 29 and 33 are shown herein as rectangular in cross section, other cross-sectional shapes may be employed.

In this particular embodiment, each of the runners 29 and 33 has a substantially flat and downwardly facing surface of approximately 13 square inches. The front and rear ends of each runner are curved so that they cannot catch the pile of carpeting or the raised edges of tiles as said chair is moved across the floor. The total floor engaging surface of the legs on an average four-legged chair does not exceed four square inches.

In one embodiment of the invention, the crossrods 18 and 23 (FIG. 3) are engaged by a channel-shaped, steel bridge member 34 having a web 36 and a pair of flanges 37 and 38 which are parallel with eachother and perpendicular to the web 36. The crossrod 18 is preferably welded at zones 39 to the flange 37 and at zones 40 to the web 36. The cross-rod 23 is welded to the flange 38 at zones 42 and to the web 36 at zones 41. The outermost ones of the weld zones 39 and 42 are spaced inwardly from the end of the bridge member 34, thereby spacing such outermost welds from the points of maximum deflection of, and stress upon, the crossrods 18 and 23, which points are located at the lengthwise edges of said bridge member. Thus, the chance of breaking the outermost welds due to stress upon and deflection of the crossrods is at least reduced.

A mounting plate 43, (FIGS. 3 and 4), preferably fabricated from rigid steel plate, is rigidly secured to the seat portion 11 of the chair 10 by means of screws 44 which are slidably received through openings 46 in the plate 43 and threadedly received into openings 47 in the seat portion 11. The web 36 of the bridge member 34 is rigidly secured to the mounting plate 43 by means of the nuts and bolts 48, but such securing could be effected by a weld. The bends in the mounting plate 43 are merely to accommodate same to the curved shape of the lower surface of the seat portion 11.

The bridge member 34 and the crossrods 18 and 23 comprise a rigid crossbar means whereby the legs 19, 20, 24 and 25 are secured to the mounting plate 43.

The bridge member 51, illustrated in FIG. 6, is comprised of a pair of channel members 52 and 53 having webs 54 and 55, respectively. The flanges 56 and 57 of channel member 52 are preferably spaced an appropriate distance from the flanges 58 and 59, respectively, of the channel member 53 when their respective webs 54 and 55 are bearing against diametrically opposite sides of the crossrods 18A and 23A. Thus, the

- channel members 52 and 53 can be secured to each other and, at the same time, secured to the crossrods 18A and 23A by two lines of welding on opposite sides of the bridge member 51. There may be occasions when this form of structure would be desirable to improve strength or achieve the same strength with slightly lighter gauge materials.

Moreover, there may be circumstances where the central portions of the crossrods can be omitted so that the upper ends of the legs are integral with small pieces of rod which are secured within the opposite ends of the bridge member 51.

The bolt 63, which secures the bridge member 51 to the mounting plate 43A, is slidably received through a spacer 64 located between the webs 54 and 55, and said bolt is engaged at its lower end by a nut 65. In all other respects, a chair having the bridge member 51 could, and preferably would, be identical with a chair having the bridge member 34.

FIG. 7 illustrates three chairs embodying the invention and arranged in stacked positions. It will be seen that the legs of an upper chair are readily nestable with the legs of a lower chair and the combination of the sloped back of the chair and the forward stepping of the legs thereof, relative to the chair below it, avoids interference between the seat and back portions. FIG. 8 merely illustrates that-the legs of the nested chairs will be substantially coplanar, as will be their runners.

FIG. 9 illustrates that an elongated base structure 71, which is substantially the same, except for width, as the base structure 15 described above with respect to FIG. 2, can be used to support a seat structure 72 which is also laterally elongated to accommodate more than one occupant. However, the same minimizing of the adverse affects of stress and strain and deflection upon the welds is retained and such elongated seat and base structure is still nestable. It will be readily apparent that other variations can be furnished, including the variation in which two seat and back combinations, as shown in FIG. 1, are placed upon the elongated base structure of FIG. 9, and such an arrangement would not affect the nesting features of this basic design.

OPERATION Although persons skilled in this art will readily understand the operation of the structures disclosed above from such disclosure, the operation thereof is briefly summarized hereinafter for the sake of convenience. A chair (FIG. 1), built as described above, can be occupied by children or adults in the same manner as a chair having a similar occupant engaging portion, but having an entirely conventional base or support structure. However, the runners 29 and 33 provide a much larger area for engagement with a supporting surface, thereby substantially reducing the pressure per unit area. This prevents harmful compression of carpet pile, dimpling of relatively soft surfaces, such as vinyl tile, and scratches on wooden surfaces, all of which are notorious problems created by conventional, four-legged chairs.

While the support elements 16 and 17 are relatively rigid, they have sufficient resilient flexibility that, for example, the crossrods 18 and 23 will tend to flex as the occupant in the chair leans frontwardly or rearwardly. This will tend to reduce fatigue experienced in using a conventional four-legged chair in which such deflections are virtually nonexistent. Such deflections of the crossrods can be permitted because the lower ends of the legs are securely anchored together. The extents and locations of the runners 29 and 33 cause the chair It) to resist backward tipping.

Because the support structure can be attached to the mounting plate by means of two or more nut and bolt combinations, and because the mounting plate 43 is secured to the seat 11 by four cap screws, base structures 15 can be stocked in stacked arrangements which require relatively little space for immediate attachment to a wide variety of the occupant engaging portions, including a seat, back and cushion. This permits decorator use of fabrics and colors in relatively small quantities without losing the advantages of large-scale production efficiency in the manufacture of the base structures.

Although a particular preferred embodiment of the invention has been disclosed in detail for illustrative purposes, it will be recognized that variations or modifications of the disclosed apparatus, including the rearrangement of parts, lie within the scope of the present invention.

The embodiment of the invention in which an exclusive property or privilege is claimed are defined as follows:

,1. Base structure for seat means having a rigid, substantially horizontal frame member comprising:

elongated, rigid, downwardlyopening, channelshaped bridge means having substantially flat plate means with first and second, integral and spaced projection means extending downwardly from said plate means; connection means adapted to rigidly secure said bridge means to said frame member; a pair of similar, rigid, spaced, parallel and U-shaped elements, each element having a crossrod and legs extending perpendicularly and in substantially the same direction from said cross-rod, said U-shaped elements defining spaced and substantially parallel planes, said crossrods being disposed between' said projection means and extending in the elongated direction of said bridge means, said cross-rods being rigidly connected to said bridge means by being located at and fixedly secured in the respective corners defined by the junctures of said first and second projection means with said plate means; and a pair of elongated, substantially straight runner means, each of said runner means being rigidly secured near the center thereof to the free end of one leg of each U-shaped element, said runner means being substantially parallel with each other and transverse of said planes.

2. A base structure according to claim 1 wherein said projection means extend in the longitudinal direction of the bridge means and comprise parallel, integral flanges extending in the same direction from and substantially perpendicularly to said plate means; and

wherein said crossrods are secured by welds to said flanges and said plate means at intervals lengthwise thereof, said welds being spaced from the lengthwise ends of said bridge means.

3. A base structure according to claim 1 wherein said bridge means is substantially channel-shaped and said projection means are flanges, said crossrods being rigidly secured to said flanges and said plate means;

' wherein said runner means are located on the outside of said legs; and

wherein the free ends of said legs are flattened and offset so that the inner surface of each runner means is substantially located outside of a plane defined by the outside surfaces of the two legs secured to such runner means.

4. A base structure according to claim lwherein said crossrods are welded to said bridge means and the welds are spaced substantially from the points on said crossrods of maximum deflection and stress; and

wherein said connection means includes a rigid mounting plate secured to said frame member and said bridge means.

5. A base support structure according to claim 1 wherein the adjacent legs of said U-shaped elements are substantially parallel and are laterally spaced from each other by a distance slightly greater than twice the thickness of each leg; wherein said crossrods extend beyond opposite edges of the seat means by a distance slightly greater than the thickness of said legs; and wherein said runner means are disposed on the outer sides of said legs outwardly of a plane defined by the outer surfaces of said legs whereby one said seat means having a said base structure can be stacked upon another of said seat means attached to a said base structure with the legs of one U-shaped element of said one base structure being nested within the'legs of said other base structure.

6. A base structure according to claim 1 wherein said runner means have substantially flat lower surfaces adapted to engage a substantially flat supporting surface, the combined area of said lower surfaces being in the range of between 10 and square inches.

7. In a seat structure having seat means provided with a rigid and substantially horizontal frame member on the underside thereof and a vertically extending base structure fixedly secured to the frame member,

said base structure being adapted to be supported on a substantially horizontal support surface for maintaining said seat means elevated above said surface, the improvement wherein said base structure comprises:

elongated, rigid, downwardly opening, channelshaped bridge means fixedly secured to said horizontal frame member, said bridge means having a substantially flat plate means and first and second spaced projection means fixedly connected to said fiat plate means adjacent the opposite longitudinal edges thereof, said projection means extending downwardly from said fiat plate means being positioned closely adjacent but laterally spaced from one another and each including a sub- 1 stantially horizontal portion fixedly connected to said bridge means and extending outwardly to a point disposed adjacent an edge of said seat means, the horizontal portions of said first pair of leg members being disposed between said projection means and being located atv and fixedly secured in'the respective corners defined by the junctures of said first and second projection means with said plate means, each of said leg members also including a substantially vertical portion integrally connected to the outer end of said horizontal portion and extending vertically downwardly, whereby the vertical portions of said leg members are substantially perpendicular to their respective horizontal portions;-

first elongated and substantially straight runner member fixedly and rigidly secured to the lower end of the vertical portions of said first pair of leg members, the lower ends of said vertical portions being fixedly secured to said runner substantially near the center thereof, said runner extending substantially horizontally in a direction substantially perpendicular to the longitudinal direction of said fixedly secured to said bridge means adjacent the adjacent an edge of said seat means, the horizontal portions of said second pair of leg members being -Qi 'ai ii .nr iwt n ea .bsins,

loeated at and fixedly secured in the respective comers defined by the junctures of said first and second projection means with said plate means, each of said leg members also including a substantially vertical portion having the upper end thereof rigidly connected to the outer end of said horizontal portion, said vertical portions being substantially perpendicular to their respective horizontal portions; and

a second elongated and substantially straight runner member rigidlysecured to the lower ends of the vertical portions of said second pair of leg members, said lower ends of said vertical portion being secured to said second runner member substantially near the center thereof, and said second runner member also extending substantially horizontally in a direction substantially perpendicular to the longitudinal direction of said bridge means, whereby said first and second mnner members are substantially parallel to one another.

8. A seat structure according to claim 9,

wherein one of the legs of said first pair and one of the legs of said second pair are integrally connected to form a first substantially U-shaped member; and

wherein the other leg of said first pair and the other leg of said second pair are also integrally connected to form a second substantially U-shaped member disposed closely adjacent but laterally spaced from said first U-shaped' member in parallel relationship therewith.

9. Base structure for seat means having a rigid substantially horizontal frame member comprising:

elongated, rigid bridge means having substantially fiat plate means with first and second, integral and spaced projection means extending downwardly from said plate means; 1

connection means adapted to rigidly secure said bridge means to said frame member;

a pair of similar, rigid, spaced and U-shaped elements, each element having a crossrod and legs extending perpendicularly and in substantially the same direction from said crossrod, said U-shaped elements defining spaced and substantially parallel planes, each crossrod extending in theelongated direction of and being rigidly connected to said bridge means and located adjacent one of said projection means;

said bridge means comprising a pair of channel members disposed on opposite sides of said crossrods and opening toward each other, said channel members having flanges welded to each other and to said crossrods; and

a pair of elongated, substantially straight runner means, each of said runner means being rigidly secured near the center thereof to the free end of one leg of each U-shaped element, said runner means being substantially parallel with each other and transverse of said planes. 

1. Base structure for seat means having a rigid, substantially horizontal frame member comprising: elongated, rigid, downwardly opening, channel-shaped bridge means having substantially flat plate means with first and second, integral and spaced projection means extending downwardly from said plate means; connection means adapted to rigidly secure said bridge means to said frame member; a pair of similar, rigid, spaced, parallel and U-shaped elements, each element having a crossrod and legs extending perpendicularly and in substantially the same direction from said cross-rod, said U-shaped elements defining spaced and substantially parallel planes, said crossrods being disposed between said projection means and extending in the elongated direction of said bridge means, said cross-rods being rigidly connected to said bridge means by being located at and fixedly secured in the respective corners defined by the junctures of said first and second projection means with said plate means; and a pair of elongated, substantially straight runner means, each of said runner means being rigidly secured near the center thereof to the free end of one leg of each U-shaped element, said runner means being substantially parallel with each other and transverse of said planes.
 2. A base structure according to claim 1, wherein said projection means extend in the longitudinal direction of the bridge means and comprise parallel, integral flanges extending in the same direction from and substantially perpendicularly to said plate means; and wherein said crossrods are secured by welds to said flanges and said plate means at intervals lengthwise thereof, said welds being spaced from the lengthwise ends of said bridge means.
 3. A base structure according to claim 1 wherein said bridge means is substantially channel-shaped and said projection means are flanges, said crossrods being rigidly secured to said flanges and said plate means; wherein said runner means are located on the outside of said legs; and wherein the free ends of said legs are flattened and offset so that the inner surface of each runner means is substantially located outside of a plane defined by the outside surfaces of the two legs secured to such runner means.
 4. A base structure according to claim 1 wherein said crossrods are welded to said bridge means and the welds are spaced substantially from the points on said crossrods of maximum deflection and stress; and wherein said connection means includes a rigid mounting plate secured to said frame member and said bridge means.
 5. A base support structure according to claim 1 wherein the adjacent legs of said U-shaped elements are substantially parallel and are laterally spaced from each other by a distance slightly greater than twice the thickness of each leg; wherein said crossrods extend beyond opposite edges of the seat means by a distance slightly greater than the thickness of said legs; and wherein said runner means are disposed on the outer sides of said legs outwardly of a plane defined by the outer surfaces of said legs whereby one said seat means having a said base structure can be stacked upon another of said seat means attached to a said base structure with the legs of one U-shaped element of said one base structure being nested within the legs of said other base structure.
 6. A base structure according to claim 1 wherein said runner means have substantially flat lower surfaces adapted to engage a substantially flat supporting surface, the combined area of said lower surfaces being in the range of between 10 and 20 square inches.
 7. In a seat structure having seat means provided with a rigid and substantially horizontal frame member on the underside thereof and a vertically extending base structure fixedly secured to the frame member, said base structure being adapted to be supported on a substantially horizontal support surface for maintaining said seat means elevated above said surface, the improvement wherein said base structure comprises: elongated, rigid, downwardly opening, channel-shaped bridge means fixedly secured to said horizontal frame member, said bridge means having a substantially flat plate means and first and second spaced projection means fixedly connected to said flat plate means adjacent the opposite longitudinal edges thereof, said projections extending downwardly from said flat plate means and being spaced substantially inwardly from the outer edges of said seat means which extend in generally the same direction as the longitudinal edges of said flat plate means; a first pair of substantially parallel leg members fixedly interconnected to said bridge means adjacent one longitudinal end thereof, said leg members being positioned closely adjacent but laterally spaced from one another and each including a substantially horizontal portion fixedly connected to said bridge means and extending outwardly to a point disposed adjacent an edge of said seat means, the horizontal portions of said first pair of leg members being disposed between said projection means and being located at and fixedly secured in the respective corners defined by the junctures of said first and second projection means with said plate means, each of said leg members also including a substantially vertical portion integrally connected to the outer end of said horizontal portion and extending vertically downwardly, whereby the vertical portions of said leg members are substantially perpendicular to their respective horizontal portions; a first elongated and substantially straight runner member fixedly and rigidly secured to the lower end of the vertical portions of said first pair of leg members, the lower ends of said vertical portions being fixedly secured to said runner substantially near the center thereof, said runner extending substantially horizontally in a direction substantially perpendicular to the longitudinal direction of said bridge means; a second pair of substantially parallel leg members fixedly secured to said bridge means adjacent the oppoSite end thereof, said second pair of leg members also being closely adjacent but laterally spaced from one another and each including a substantially horizontal portion fixedly secured to said bridge member and extending outwardly to a point adjacent an edge of said seat means, the horizontal portions of said second pair of leg members being disposed between said projection means and being located at and fixedly secured in the respective corners defined by the junctures of said first and second projection means with said plate means, each of said leg members also including a substantially vertical portion having the upper end thereof rigidly connected to the outer end of said horizontal portion, said vertical portions being substantially perpendicular to their respective horizontal portions; and a second elongated and substantially straight runner member rigidly secured to the lower ends of the vertical portions of said second pair of leg members, said lower ends of said vertical portion being secured to said second runner member substantially near the center thereof, and said second runner member also extending substantially horizontally in a direction substantially perpendicular to the longitudinal direction of said bridge means, whereby said first and second runner members are substantially parallel to one another.
 8. A seat structure according to claim 9, wherein one of the legs of said first pair and one of the legs of said second pair are integrally connected to form a first substantially U-shaped member; and wherein the other leg of said first pair and the other leg of said second pair are also integrally connected to form a second substantially U-shaped member disposed closely adjacent but laterally spaced from said first U-shaped member in parallel relationship therewith.
 9. Base structure for seat means having a rigid substantially horizontal frame member comprising: elongated, rigid bridge means having substantially flat plate means with first and second, integral and spaced projection means extending downwardly from said plate means; connection means adapted to rigidly secure said bridge means to said frame member; a pair of similar, rigid, spaced and U-shaped elements, each element having a crossrod and legs extending perpendicularly and in substantially the same direction from said crossrod, said U-shaped elements defining spaced and substantially parallel planes, each crossrod extending in the elongated direction of and being rigidly connected to said bridge means and located adjacent one of said projection means; said bridge means comprising a pair of channel members disposed on opposite sides of said crossrods and opening toward each other, said channel members having flanges welded to each other and to said crossrods; and a pair of elongated, substantially straight runner means, each of said runner means being rigidly secured near the center thereof to the free end of one leg of each U-shaped element, said runner means being substantially parallel with each other and transverse of said planes. 